Safety syringes

ABSTRACT

Syringes are disclosed herein incorporating a variety of safety mechanisms for protecting the users from accidental needle stick. In certain embodiments, the syringes incorporate retractable carriages that can be retracted into the syringe barrels by engaging with the plungers. The carriages are configured to receive different needle hubs having any number of needle sizes. In certain other embodiments, the carriages are spring loaded so that as the plungers disengage the carriages from the syringe barrels, the springs automatically retract the needles into the barrels. Still in certain other embodiments, needle hubs with spring loaded needles are used with the syringes. The needles are retracted into the barrels when the plungers activate certain mechanisms incorporated into the hubs to thereby release the needles. Still yet in certain other embodiments, sheaths are used to cover needle tips.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of application entitled “SAFETYSYRINGES”, filed on Jan. 30, 2004, having attorney docket number51394/THD/K163, Ser. No., identified on Applicant's postcard, Ser. No.10/769,067, which claims priority to German Utility Model DE 20 303 231U1, filed on Feb. 27, 2003, the contents of the related applications areexpressly incorporated herein by reference.

Safety syringes for minimizing accidental contact with users aregenerally discussed herein with particular discussions extended tosafety syringes having manual and automatic retractable carriages orsheaths.

BACKGROUND

Syringes are used for injecting fluids and for withdrawing fluids fromfluid carrying sources. In an effort to reduce the transfer ofcommunicable diseases, safety features were added to commerciallyavailable syringes to minimize accidental contact or sticking with usedneedle tips.

Principally among these safety features are tip protectors and syringeswith retractable carriages. Broadly speaking, in the tip protectortechnology, a protective element is mounted over a needle and configuredto cover the needle tip of the needle subsequent to an injection toblock the needle tip. The protective element may be activated manuallyto cover the needle tip or automatically by way of releasing a spring tothen push the protective element over the needle tip.

In the retractable carriage technology, the syringe is fitted with amovable carriage at a distal end of the syringe barrel. The carriage mayincorporate a fixed needle or a Luer tip for mounting a needle hub witha needle. After an injection, the carriage can be retracted into theinterior cavity of the syringe barrel along with the needle to preventneedle stick. More particularly, following an injection, the carriage istypically engaged by a plunger and retracted into the interior cavity ofthe barrel by pulling onto the plunger in the opposite or proximaldirection. Alternatively, the carriage is disengaged from the barrel bythe plunger and a spring automatically retracts the carriage into theinterior cavity of the barrel.

Although the prior art safety features for syringes are useful, thesafety syringes described elsewhere herein are better alternatives.Among other things, the prior art safety devices have shortcomings inthat the air cannot be completely expelled from the syringe barrel priorto aspirating fluid without triggering the safety mechanism by theplunger. This premature triggering, when attempting to fill the device,makes the prior art syringe ineffective and frustrates the health careworker trying to use it.

SUMMARY

The present invention may be implemented by providing a syringe assemblycomprising a syringe comprising a barrel having an open proximal end anda barrel end surface at a distal end, a plunger slidably disposed in thebarrel comprising a push flange, and a plunger tip comprising a plungertip end surface positioned on a distal end of the plunger; the pushflange being spaced apart from the plunger tip end surface by a firstdistance; a sheath unit comprising a sheath cover telescopicallydisposed over and removably secured to an inner shell; said inner shellcomprising an interior surface defining an interior cavity; and a springcompressed by a shoulder on the sheath cover and a shoulder on the innershell. The barrel of the syringe is disposed, at least in part, in thecavity of the inner shell; and wherein the plunger comprises threeplunger positions including a first plunger position in which theplunger tip positioned on the plunger is spaced apart from the barrelend surface; a second plunger position in which the plunger tip contactsthe barrel end surface; and a third plunger position in which the pushflange on the plunger moves a distal direction relative to the plungertip distal end surface such that the push flange is now spaced apartfrom the plunger tip distal end surface by a second distance, which isless than the first distance.

In yet another aspect of the invention, there is provided a syringeassembly comprising a syringe comprising a barrel and a plunger having aplunger tip disposed inside the barrel; wherein the plunger comprises atapered trigger element disposed distal of a plunger push surface andthe barrel comprising a barrel end surface comprising an orifice; asheath unit comprising a sheath cover comprising at least one triggerlever comprising a pivot point and a trigger tip; the sheath cover beingtelescopically disposed over an inner shell and removably held theretoby a detent engagement between the trigger lever and an engagementsurface on the inner shell; and a spring held in a compressedconfiguration by the detent engagement. The syringe is disposed, atleast in part, inside the inner shell; and wherein the plunger tip abutsthe barrel end surface and the tapered trigger element on the plungercontacts the trigger lever but does not sever the detent engagement.

In still yet another aspect of the invention, there is provided asyringe assembly comprising a syringe disposed, at least in part, insidean interior cavity of a sheath unit; the syringe comprising a barrelcomprising an open proximal end and a closed distal end comprising anorifice; a plunger comprising a push flange, a tapered actuator, and atip holder comprising a plunger tip mounted thereon slidably disposedinside the barrel; the push flange being spaced apart from a distalexterior wall surface of the plunger tip by a first distance; and thesheath unit comprising a spring and a sheath cover telescopicallydisposed over an inner shell and held to the inner shell by anengagement between a receptacle on a trigger lever located on the sheathcover engaging an ear located on the inner shell; the spring being heldin a compressed configuration by the engagement. The tapered actuatordisengages the ear from the receptacle when the plunger moves distallyand the push flange is spaced apart from the distal exterior wallsurface by a second distance, which is less than the first distance.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention willbecome appreciated as the same become better understood with referenceto the specification, claims and appended drawings wherein:

FIG. 1 is a semi-schematic cross-sectional view of a syringe with amanual retractable carriage provided in accordance with aspects of thepresent invention;

FIG. 2 is a semi-schematic cross-sectional view of the syringe of FIG. 1with the carriage engaged by a plunger for retracting into the barrel ofthe syringe;

FIG. 2 a is a semi-schematic cross-sectional view of an alternativeplunger tip provided in accordance with aspects of the presentinvention;

FIG. 2 b is a semi-schematic exemplary plan view of two alignment platesincorporated by the syringe of FIG. 1;

FIG. 3 is a semi-schematic cross-sectional view of an alternativesyringe with a manual retractable carriage provided in accordance withaspects of the present invention;

FIG. 4 is a semi-schematic cross-sectional view of the syringe of FIG. 3with the carriage engaged by a plunger for retracting into the barrel ofthe syringe;

FIG. 5 is a semi-schematic cross-sectional view of another alternativesyringe with a manual retractable carriage provided in accordance withaspects of the present invention;

FIG. 6 is a semi-schematic cross-sectional view of the syringe of FIG. 5with the carriage engaged by a plunger for retracting into the barrel ofthe syringe;

FIG. 7 is a semi-schematic cross-sectional view of yet anotheralternative syringe with a manual retractable carriage provided inaccordance with aspects of the present invention;

FIG. 8 is a semi-schematic cross-sectional view of the syringe of FIG. 7with the carriage engaged by a plunger for retracting into the barrel ofthe syringe;

FIG. 9 is a semi-schematic cross-sectional view of yet anotheralternative syringe with a manual retractable carriage provided inaccordance with aspects of the present invention;

FIG. 10 is a semi-schematic cross-sectional view of the syringe of FIG.9 with the carriage engaged by a plunger for retracting into the barrelof the syringe;

FIG. 11 is a semi-schematic cross-sectional view of a syringe with aspring loaded carriage provided in accordance with aspects of thepresent invention;

FIG. 12 is a semi-schematic cross-sectional view of the syringe of FIG.1 with the carriage disengaged and ready for retraction;

FIG. 13 is a semi-schematic cross-sectional view of the syringe of FIG.11 with the carriage retracted inside the barrel;

FIG. 14 is a semi-schematic cross-sectional view of an alternativesyringe with a spring loaded carriage provided in accordance withaspects of the present invention;

FIG. 15 is a semi-schematic cross-section view of the syringe of FIG. 14with the carriage disengaged and ready for retraction;

FIG. 16 is a semi-schematic cross-sectional view of another alternativesyringe with a spring loaded carriage provided in accordance withaspects of the present invention;

FIG. 17 is a semi-schematic cross-sectional view of the syringe of FIG.16 with the carriage disengaged and ready for retraction;

FIG. 18 is a semi-schematic partial cross-sectional view of a syringewith a needle hub having a spring loaded retractable needle provided inaccordance with aspects of the present invention;

FIG. 19 is a semi-schematic partial enlarged view of the needle hub ofFIG. 18;

FIG. 20 is a semi-schematic partial cross-sectional view of the syringeof FIG. 18 with the needle retracted partially into the barrel;

FIG. 21 is a semi-schematic partial cross-sectional view of analternative syringe with a needle hub having a spring loaded retractableneedle provided in accordance with aspects of the present invention;

FIG. 22 is a semi-schematic partial cross-sectional view of anotheralternative syringe with a needle hub having a spring loaded retractableneedle provided in accordance with aspects of the present invention;

FIG. 23 is a semi-schematic partial enlarged view of an alternativeneedle hub having a spring loaded retractable needle provided inaccordance with aspects of the present invention;

FIG. 24 is a semi-schematic side view of another alternative safetysyringe provided in accordance with aspects of the present invention;

FIG. 25 is a semi-schematic cross-section side view of the safetysyringe of FIG. 24;

FIG. 26 is a combination top view and cross-sectional side view of analternative actuator mountable on the plunger of FIG. 24;

FIG. 27 is a semi-schematic cross-sectional side view of the safetysyringe of FIG. 25 taken along line F27-F27;

FIG. 28 is the syringe of FIG. 27 in a retracted configuration;

FIG. 29 is a semi-schematic perspective view of an inner shell of FIG.24 provided in accordance with aspects of the present invention; and

FIG. 30 is the sheath unit of FIG. 24 useable with an alternativesyringe.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of the presently preferredembodiments of safety syringes provided in accordance with practice ofthe present invention and is not intended to represent the only forms inwhich the present invention may be constructed or utilized. Thedescription sets forth the features and the steps for constructing andusing the safety syringes of the present invention in connection withthe illustrated embodiments. It is to be understood, however, that thesame or equivalent functions and structures may be accomplished bydifferent embodiments that are also intended to be encompassed withinthe spirit and scope of the invention. Also, as denoted elsewhereherein, like element numbers are intended to indicate like or similarelements or features.

Referring now to FIG. 1, an exemplary syringe 10 with a retractablecarriage 12 provided in accordance with aspects of the present inventionis shown. In one exemplary embodiment, the syringe 10, which may be ofany standard sizes such as 5 ml or 10 ml, comprises a barrel 14, aproximal end 16 with a grip flange 18, and a distal end 20 with anopening 22 for receiving a standard needle hub having a needle attachedthereto (not shown).

The barrel 14 defines a wall surface which has an exterior surface 24and an interior surface 26, which defines an interior cavity 28.Positioned in the interior cavity 28 are the plunger 30, which has apush flange 32 on one end and a plunger tip or seal 34 on another end,and the carriage 12. In one exemplary embodiment, the carriage 12comprises a male Luer tip 36, a sealing ring 38, and a pair ofproximally extending arms 40 a, 40 b. The sealing ring 38 is configuredto seal against the interior surface 26 of the barrel 14 and incombination with a portion of the interior surface 26 of the barrel 14defines a volume enclosure, which is variable depending on the positionof the plunger 30 and plunger tip 34 relative to the barrel. A lumen 42is defined through the axial center of the carriage 12 for fluidcommunication between the interior cavity 28 of the syringe andexteriorly of the barrel 14 variable volume enclosure. The plunger tip34 is dynamically sealed against the interior surface 26 of the barrierby well known methods.

The proximally extending arms 40 a, 40 b are cantilevered to the base ofthe sealing ring 38 by a pair of integrally molded bridges 42 a, 42 b(FIG. 2). The cantilevered configuration permit the arms 40 a, 40 b toflex radially inwardly in the direction of the longitudinal axis definedby the lengthwise central axis of the barrel for reasons discussedfurther below. Just proximal of the bridges 42 a, 42 b are the raisedridges 44 a, 44 b and the male detents 46 a, 46 b, which matingly engagewith the female detents 48 a, 48 b formed in the interior surface 26 ofthe barrel 14 when the carriage 12 is in the ready to use position. Twoactuated ramps 50 a, 50 b are positioned further proximal of the maledetents 46 a, 46 b. In one exemplary embodiment, the actuated ramps 50a, 50 b incorporate diagonal faces for imparting a pair of componentforces to the arms 40 a, 40 b when pushed by the plunger 30 to flex thearms 40 a, 40 b radially inwardly, as further discussed below. Theactuated ramps 50 a, 50 b terminate in a hook-like configuration forengaging with the shroud 62 (FIG. 1). The barrel 14, plunger 30,carriage 12, and plunger tip 34 may be made from known materialscurrently used in the art.

In one exemplary embodiment, the barrel 14 comprises two taperedsections. A first tapered section 52 is formed in the interior cavity 28of the barrel and acts as a shoulder to stop the distal or forwardadvancement of the plunger tip 34. The second tapered section 54 isformed on the exterior surface 24 of the barrel 14 for aesthetic appealthat may otherwise be eliminated. Alternatively, the tapered sections52, 54 may be squared, or may incorporate a combination of a squaredfinish and a tapered finish. The barrel is preferably transparent orsemi-transparent and may include indicia such as labeling, markings, orother features for references.

In one exemplary embodiment, the plunger 30 incorporates a pair ofelongated plates 55 a, 55 b having a plus (“+”)-shaped cross-section.One or more push plates 56 may be formed on plunger 30 forreinforcement. A distally projecting post or tip holder 58 is positioneddistal of the one or more push plates 56 for positioning the plunger tip34 thereon. A plunger disc 60 is formed on the distally projecting post58 and is preferably spaced from the most distal push plate 56 by a gap,which should be of sufficient width for accommodating a portion of theplunger tip 34, as further discussed below. A generally cylindricalshroud 62 is positioned distal of the plunger disc 60 having a pusherend 64 (FIG. 2) and a pair of receiving slots 66. In one exemplaryembodiment, the pusher end 64 and the plunger disc 60 each comprises atapered surface for reasons further discussed below. The receiving slots66 should have a dimension sufficient to receive the hook-like ends ofthe actuated ramps 50 a, 50 b.

The shroud 62 comprises a distal end surface 67 having a pair ofopenings 69 for receiving the proximally extending arms 40 a, 40 b ofthe carriage 12. The plunger tip 34 comprises a bore 68 for receivingthe shroud 62. In one exemplary embodiment, the bore 68 of the plungertip comprises a first diameter section 70, a second diameter section 72,and a third diameter section 74 (FIG. 2). However, the internal bore 68can have a same diameter by modifying the dimensions of the post 58,shroud 62, and/or carriage 12. An inwardly extending ring 76 is formedon the proximal end of the plunger tip 34 and sized to form asize-on-size friction fit with the distally projecting post 58 of theplunger 30. A second inwardly extending ring 78 spaced from the firstinwardly extending ring 76 is positioned at the transition between thesecond diameter section 72 and the third diameter section 74 of theplunger tip. The space or gap 80 between the first 76 and second 78inwardly extending rings functions as an activation gap and isconfigured to receive the plunger disc 60 when the plunger 30 isadvanced distally to activate or retract the carriage 12, as furtherdiscussed below.

In an alternative plunger tip 34′ embodiment (FIG. 2 b), the secondinwardly extending ring 78 may be omitted and the proximal end 61 ofshroud 62′ extended or moved further proximal to be adjacent the distalside of extending ring 76′. This eliminates the need for a gap 80 andsimplifies the form of plunger tip 34′. The alternative plunger tip 34′otherwise functions the same as the plunger tip 34 of FIGS. 1 and 2.

To use the syringe 10, a commercially available needle attached to aneedle hub (not shown) is first mounted onto the Luer tip 36. Becausethe syringe 10 has a Luer tip 36 and not a permanently attached needleon the carriage 12, different needle sizes may be mounted onto the Luertip for aspirating, withdrawing a sample, or performing an injection.Preferably, if the syringe is used to withdraw a sample, the needle withthe needle hub should include a tip protector or clip for covering theneedle tip.

With the barrel 14 filled with a medicinal fluid, which can be anynumber of fluids, to a desired volume and the needle injected into asubject, the plunger 30 is advanced distally with a distally directedforce F_(D) in the direction of the needle to discharge the fluid. Theinjection is completed when the plunger tip 34 contacts the shoulder orfirst tapered section 52 of the barrel 14. At this point, preferably theneedle is withdrawn from the subject by pulling on the plunger 30 viathe push flange 32 while pushing the barrel 14 distally against thepatient's skin. The needle and carriage 12 retraction into the barrelare simultaneously accomplished as described in detail below.Alternatively, the needle can be withdrawn from the patient prior toretracting the needle into the barrel 14.

To retract the carriage 12 with the needle still mounted thereto, theplunger 30 is further advanced distally with an activated force F_(A)sufficient to bend the proximally extending arms 40 a, 40 b inwardly atthe bridges 42 a, 42 b, which act as fulcrum points. In one exemplaryembodiment, the activated force F_(A) is greater than the distallyadvancing force F_(D) so that a user in using the syringe 10 can feel aclear delineation between injecting a fluid and withdrawing the carriage12.

The bending of the arms 40 a, 40 b occur when the pusher end 64 of theshroud 62, which preferably comprises a tapered face, contacts theactuated ramps 50 a, 50 b of the arms 40 a, 40 b and impart a pair ofcomponent forces. The arms 40 a, 40 b bend radially inwardly and themale detents 46 a, 46 b separate from the female detents 48 a, 48 b asthe plunger 30 advances distally under an actuated force F_(A). The armscontinue to bend as until the hook-like ends of the actuated ramps 50 a,50 b latch with the receiving slots 66 a, 66 b located in of the shroud62. When the activated force F_(A) is no longer applied, the arms 40 a,40 b, due to their resiliency, snap radially outwardly a small radialdistance to securely engage with the slots 66 a, 66 b (FIG. 2).

During the activation step, the plunger disc 60 pushes against theinwardly extending ring 76 of the plunger tip 34 until the ring 76, dueto its resiliency, pops over the disc 60 so that the disc can then moveinto the activated space 80. As readily apparent, subsequent to theplunger tip 34 abutting the shoulder 52 of the barrel and stop moving,the plunger 30 may still move distally relative to the plunger tip todisengage the carriage 12 from the barrel 14. Unrestrained, the carriage12 and needle (not shown) can then be retracted into the interior cavity28 of the barrel 14 by grasping and pulling on the push flange 32proximally to retract the needle into the barrel 14.

To prevent retracting the carriage 12 too far into the barrel 14 andpossibly dislodge the carriage 12 from the barrel 14 and to also preventthe needle from protruding back out the distal end 20 of the barrel, inone exemplary embodiment, a stop ring 82 (FIG. 2), which may comprise anannular projection on the interior surface 26 of the barrel near thegrip flange 18, may be incorporated to hold the plunger 30 in thecompletely retracted position. The plunger 30 may include a notch 84along each edge of the elongated plates 55 a, 55 b to provide a breakingpoint for breaking off the plunger and avoiding accidentally pushing theneedle distally into an unprotected position. Once the carriage 12 isretracted into the barrel and the plunger 30 broken off, the syringe maybe safely disposed of per standard protocols.

For aligning the hooks on the actuated ramps 50 a, 50 b of the carriage12 with the receiving slots 66 a, 66 b located on the shroud 62 of theplunger 30, alignment plates 86 a, 86 b may be incorporated at theproximal end 16 of the barrel 14. The alignment plates 86 a, 86 b may beintegrally molded with the push flange 18 via living hinges 88 and thenglued, welded, or engaged to the push flange 18 by detents.Alternatively, the alignment plates 86 a, 86 b may be separatelyattached to the push flange 18 via adhesive, welding, or detents withoutthe living hinges 88.

Referring to FIG. 2 a, which is an exemplary plan view of the alignmentplates 86 a, 86 b, each alignment plate 86 a or 86 b comprises agripping portion 90 and a semi-circular portion 92 comprising a slot 94and a part of a slot 96. The two alignment plates 86 a, 86 b cometogether at a parting line and the two part slots 96 on each alignmentplate makes a whole slot. The two whole slots 94 are sized to receiveone rectangular plate 55 a of the plunger 30 while the partial slots 96together receive the other rectangular plate 55 b of the plunger 30.Cooperation between the alignment plates 86 a, 86 b and the rectangularplates 55 a, 55 b prevents the plunger 30 from angularly rotating andmisaligning the hooks on the actuated ramps 50 a, 50 b with thereceiving slots 66 a, 66 b located on the shroud 62.

Turning now to FIG. 3, an alternative manual retractable syringe 98provided in accordance with aspects of the present invention is shown.The syringe 98 has features that are similar with features describedabove for the syringe 10 shown with reference to FIGS. 1-2A with theexception of the plunger tip 100 and the manner in which the plunger tipengages and interacts with the plunger 30. In the present syringe 98embodiment, the shroud 62 incorporates two openings 102 a, 102 b at thedistal end surface 67 for receiving the proximally extending arms 40 a,40 b. The plunger tip 100 comprises a bore 101 having a substantiallyuniform inside diameter for receiving the shroud 62. An inwardlyextending ring 104 is incorporated at the proximal end of the plungertip 100 and sized to form a size-on-size friction fit with the distallyprojecting post 58 of the plunger 30. In the ready to use configurationof FIG. 3, the inwardly extending ring 104 abuts the plunger disc 106located on the post 58 of the plunger 30, which in the presentembodiment does not incorporate a tapered face. A shroud 62 comprising apair of receiving slots 66 and pusher end 64 is disposed inside the bore101 of the plunger tip 100 for engaging with the hooks on the carriage12 and retracting the same into the barrel 14.

The syringe 98 may be used and the carriage 12 may be retracted into thebarrel 14 in the same manner as described above with reference to thesyringe 10 of FIGS. 1 and 2. More particularly, following an injection,the distal end of the plunger tip 100 abuts the barrel shoulder 52 andthe proximally extending arms 40 a, 40 b of the carriage 12 project intothe openings 69 of the distal end surface 67 of the shroud 62. Toretract the carriage 12, an activated force F_(A) is then applied on theplunger 30 to further advance the plunger distally relative to thedistal end of the plunger tip 100. This activated force F_(A) causes thepusher end 64 of the shroud 62 to exert a pair of component forces tothe actuated ramps 50 a, 50 b, which then bends the proximally extendingarms 40 a, 40 b radially inwardly. At the same time, the plunger disc106 pushes against the inwardly extending ring 104 and compresses theplunger tip 100 (FIG. 4).

The carriage 12 may be withdrawn proximally into the barrel 14 when themale detents 46 a, 46 b disengage from the female detents 48 a, 48 b andthe hooks on the end of the arms 40 a, 40 b engage the receiving slots66 located on the shroud 62. During the retraction procedure, theplunger tip 100 will expand in the distal direction until it touches orreaches near the proximal edge 108 of the side ridges 44 a, 44 b of thecarriage 12.

FIG. 5 shows another alternative retractable syringe 110 provided inaccordance with aspects of the present invention. The syringe 110 issimilar to the syringes of FIGS. 1-4 with the exception the carriage 112and the manner in which it engages the barrel 114 and is retracted bythe plunger 116. In one exemplary embodiment, the carriage 112incorporates a pair of actuated pistons 118 a, 118 b formed in two wells120 located on the carriage. The carriage 112 further comprises a femalelock 122 around a Luer tip 36, and a hub 124 proximal of the actuatedpistons 118 a, 118 b. The hub 124 incorporates a flange 126 for abuttingagainst the shoulder 128 located on the barrel 114 to axially align thecarriage 112 relative to the barrel 114 during engagement of thecarriage 112 to the barrel 114. The hub 124 includes a proximal surface127 having a configuration to accommodate the contour of the distal endsurface 130 of the plunger tip 132.

The carriage 112 comprises a bore 133 which defines a lumen 134 forfluid communication between the variable interior cavity 28 of thebarrel 114 and the needle (not shown) which may be mounted to thesyringe by the way of mounting a needle hub to the Luer tip 36. In oneexemplary embodiment, the bore 133 incorporates two inward projectionsfor interacting with the plunger 116. The first projection 136 islocated near the opening of the Luer tip 36 and has a tapered or slopedsurface on a proximal side. On the edge opposite the sloped surface, thefirst projection 136 preferably comprises a square finish, for reasonsfurther discussed below. The second projection 138 is formed subjacentthe two actuated pistons 118 a, 118 b. To fixedly secure the carriage112 to the barrel 114, the barrel incorporates a pair of hinged hooks140 at the distal end of the barrel. The hinge hooks 140 engage an edgeof the wells 120 located on the carriage 112 to lock the carriage to thebarrel. The hinge hooks 140 can be integrally molded on the carriage112.

In one exemplary embodiment, the plunger tip 132 incorporates a bore forreceiving the extension pin or distally projected post 142 of theplunger 116, an internal space or cavity 145, and a pair of extensionlegs 144 a, 144 b for setting a gap between certain parts of the plunger116 and of the plunger tip 132. A gap or a space 146 located in betweenthe extension legs 144 a, 144 b are configured to receive a drum 148located at the base of the extension pin 142. The gap or space 146should have sufficient depth to receive the drum 148 and not delimit orrestrict the hooks on the plunger 116 from grabbing the first projection136 located in the Luer tip 36, as further discussed below. The plunger116 also comprises a flange 147 set in the internal space 145 of plungertip 132, and in one exemplary embodiment, comprises a tapered face onits distal side to facilitate assembly over the tip holder. Flange 147secures plunger tip 132 to the plunger 116 during aspiration of a fluid.The internal space 145 should be sufficiently long to allow the flange147 to move from a proximal end within the internal space 145 to adistal end during activation so as not to delimit or hinder the hooks152 from grabbing first projection 136.

A hooking rod 150 comprising a pair of hooks 152 (FIG. 6) extends fromthe distal end of the extension pin 142 for hooking engagement with thefirst projection 136 located in the bore of the Luer tip 36. The hooks152 are configured to deflect when moved distally past a reduceddiameter created in the bore of the Luer tip by the first projection 136to grab the square face of the first projection 136 in a detentconfiguration.

To retract the carriage 112 into the interior cavity 28 of the barrel114, the plunger 116 is first advanced distally with a distally directedforce F_(D) until the distal end surface 130 of the plunger tip 132contacts the proximate surface 127 of the hub 124 of the carriage 112.In this position, the distal end of the extension pin 142 should residejust proximal of the second projection 138 located subjacent theactuated pistons 118 a, 118 b (FIG. 5). As a distally actuated forceF_(A) force is then applied to the plunger 116, the force causes theextension legs 144 a, 144 b to bend outwardly, which then moves theextension pin 142 past the second projection 138 to push the actuatedpistons 118 a, 118 b radially outwardly. Concurrently therewith, theactuated pistons 118 a, 118 b push the hinged hooks 140 on the barrel tounlock the hinged hooks 140 from the wells 120. Also at the same time,the hooks 152 on the hooking rod 150 moves distal of the firstprojection 136 to then grab the projection. When the plunger is moved inthe opposite proximal direction, the interaction between the hooks 152and the first projection retracts the carriage 112 into the barrel 114.

Although alignment plates 86 a, 86 b are not required to align parts ofthe plunger 116 to parts of the carriage 112, the plates 86 a, 86 b maybe included to prevent retracting the plunger 116 completely outside ofthe barrel 114. Alternatively or in addition thereto, a stop ring 82 maybe incorporated near the proximal end of the barrel to engage with theproximal most push plate 56 on the plunger 116 to prevent proximalmovement of the plunger. The plunger can then be broken off at thenotches 84, as previously described.

In another alternative embodiment (not shown), the hooking rod 150 andhooks 152 are eliminated from the end of the extension pin 142 of thesyringe of FIG. 5. A second set of actuated pins proximal of theexisting actuated pins 118 a, 118 b on the carriage 112 are added, whichare to be actuated and engaged by a pair of projections or ramps locatedon the extension pin 142. In this alternative embodiment, the extensionpin 142 would actuate the first set of actuated pins 118 a, 118 b todisengage the carriage 112 from the barrel 114 and the two projectionsor ramps on the extension pin 142 would latch or engage with the secondset of actuated pins to grab the carriage 112. Once the plunger isretracted, the cooperation between the ramps and the second set ofactivated pins retract the carriage proximally into the barrel. In thisembodiment, the diameter of the extension pin proximal of the twoprojections or ramps (i.e., the base of the extension pin) should havethe same diameter as the largest cross-sectional dimension of theprojections or ramps measured at their widest peaks.

FIG. 7 is another alternative retractable syringe 154 provided inaccordance with aspects of the present invention. The syringe 154 issubstantially similar to the syringe 110 described above with referenceto FIGS. 5 and 6 with the exception of the plunger tip 156 and extensionpin 158 of the plunger 160, which are different. In the presentembodiment, the extension legs 144 a, 144 b of the plunger tip areeliminated and a bore 162 incorporated with an annular ring 164. Aproximal end annular ring 166 spaced apart from the interior annularring 164 is also incorporated. The two rings define an activation spaceor gap 168 for accommodating a part of the extension pin 158, as furtherdiscussed below.

A pair of plunger discs 172, 174 are incorporated with the base 170 ofthe extension pin 158 for cooperating with the plunger tip 156. Thedistal most plunger disc 174 preferably comprises a tapered surface forfacilitating advancing the disc past the interior annular ring 164. Inone exemplary embodiment, the proximal most plunger disc 172incorporates a square finish for pushing the proximal annular ring 166of the plunger tip 156 distally when a distally directed force F_(D) isapplied. However, a slight taper, of less angular offset than the distalmost disc 174, may be incorporated by the proximal most disc 172 tofacilitate moving the disc 172 past the end annular ring 166 when anactivated force F_(A) is applied (FIG. 8).

To retract the carriage 112 into the interior cavity 28 of the barrel114, the plunger 160 is first advanced distally with a distally directedforce F_(D) until the distal end surface 130 of the plunger tip 156contacts the proximal surface 127 of the carriage 112. In this position,the distal end of the extension pin 158 should reside just proximal ofthe second projection 138 located subjacent the actuated pistons 118 a,118 b. As a distally actuated force F_(A) force is then applied on theplunger 160, the force causes the two plunger discs 172, 174 to movepast the two annular rings 166, 164 positioned inside the bore 162 ofthe plunger tip 156, which concurrently moves the extension pin 158 pastthe second projection 138 to push the actuated pistons 118 a, 118 bradially outwardly. Also concurrently therewith, the actuated pistons118 a, 118 b push the hinged hooks 140 on the barrel 114 to unlock thehinged hooks 140 from the wells 120. Also at the same time, the hooks152 on the hooking rod 150 moves distal of the first projection 136 tothen grab the projection. The carriage 112 can now be retracted bypulling on the plunger 160 in the proximal direction. The plunger 160can then be broken off as previously described.

FIG. 9 shows yet another alternative manual retract syringe 176 providedin accordance with aspects of the present invention. The syringe 176 issubstantially similar to the syringes 110, 154 described above withreference to FIGS. 5-8 with the exception of the plunger tip 178 andextension pin 183 of the plunger 180, which are different. Moreparticularly, the extension pin 183 in the present embodiment extendsdirectly from the distal most push plate 56 on the plunger 180 without abase or a drum. In addition, the plunger tip 178 has a single annularend ring 182 without internal annular rings. The extension pin 183comprises a flange 185 located just distal of the annular end ring 182.The flange 185 is preferably tapered on its distal side to facilitateassembly through the annular end ring 182, but flat on its proximal sideto secure the plunger tip 178 on plunger 180 during aspiration of afluid. The bore or cavity 184 inside the plunger tip 178 should besufficiently dimension to permit flexing of the plunger tip whencompressed by the plunger 180 (FIG. 10).

To retract the carriage 112 into the interior cavity 28 of the barrel114, the plunger 180 is first advanced distally with a distally directedforce F_(D) until the distal end surface 130 of the plunger tip 178contacts the proximal surface 127 of the carriage 112. In this position,the distal end of the extension pin 183 should reside just proximal ofthe second projection 138 located subjacent the actuated pistons 118 a,118 b. As a distally actuated force F_(A) force is then applied on theplunger 180, the force causes the push plate 56 to push against theannular ring 182 of the plunger tip 178 and compresses the plunger tip(FIG. 10). At the same time, the extension pin 183 travels past thesecond projection 138 to push the actuated pistons 118 a, 118 b radiallyoutwardly. Also, concurrently therewith, the actuated pistons 118 a, 118b push the hinged hooks 140 on the barrel 114 to unlock the hinged hooks140 from the wells 120 on the carriage 112. Also at the same time, thehooks 152 on the hooking rod 150 moves distal of the first projection136 to then grab the projection. The carriage 112 can now be retractedby pulling on the plunger in the proximal direction. The plunger canthen be broken off at the notches 84, as previously described.

Referring now to FIG. 11, an automatic needle retract syringe 186provided in accordance with aspects of the present invention is shown.The syringe 186 comprises a syringe barrel 188, a plunger 190 with aplunger tip 192, and a carriage 194 that is spring loaded with a spring196. The barrel 188 in the present embodiment comprises a grippingsection 198 having a grip flange 18 and an enlarged barrel section 200sized to receive a part of the push flange 202 on the plunger 190. Inone exemplary embodiment, the proximal end 204 of the enlarged barrelsection 200 comprises a projection or ring for engaging with theperimeter of the push flange 202 when the push flange is pushed upagainst the barrel 188 to retract the needle (FIGS. 12 and 13), asfurther discussed below. Alternatively, the diameter of the enlargedbarrel section 200 could be sized to form an interference fit with thepush flange 202 when the same is moved into the barrel to retract theneedle.

Distally of the gripping section 198 is the variable chamber section206, which stores fluid to be infused or injected and varies in volumedepending on the position of the plunger tip 192 relative to the barrel188. Distal of the variable chamber section 206 is the engagementchamber 208. The engagement chamber 208 comprises a first engagementsection 210 comprising an annular interior surface 212 that cooperateswith the carriage 194 to compress a holding tire 214, which may be madefrom any number of elastomeric rubber or of the same elastomer as theplunger tip 192. Distal thereof is the second engagement section 211.The compressed holding tire 214 acts as an anchor to hold the carriage194 in place or position, which then allows the spring 196 to becompressed between the end wall 216 at the distal end 218 of the barrel188 and the shoulder 220 located near the base 222 of the carriage 194.As readily apparent, the holding tire 214 should have a compressionforce exerted on it by the carriage 194 and the barrel 188 sufficient toresists the spring force generated by the compressed spring 196.Additional hold on the holding tire 214 can come from the projection 244located at the shoulder 241 of the barrel 188.

A passage or lumen 224 is formed at the axial center of the carriage 194to permit fluid communication between the interior cavity of the barrel188 and outside the barrel. In one exemplary embodiment, a needle 226comprising a needle tip is permanently secured to the carriage 194 viagluing the same to the carriage at the glue well 228.

In one exemplary embodiment, the plunger 190 comprises a first tubularsection 230 and a second tubular section 232, which defines an exteriorshoulder 234 therebetween. The plunger tip 192 is positioned on theexterior surface of the first tubular section 230 and abuts the exteriorshoulder 234. Interiorly, a plug 236, which can be made from anelastomer material, is compressed against the interior surface of thesecond tubular section 232 by its base section 238, which is relativelylarger than its frontal projection 240. Prior to activating the spring(FIG. 11), the distal end of the plug 236, the cylindrical end of thefirst tubular section 230, and the plunger tip 192 are substantiallyaligned so that they occupy substantially all of the head space of thevariable chamber section 206 to substantially discharge all of the fluidwithin the barrel. To facilitate this goal, the shoulder 241 between thevariable chamber section 206 and the engagement chamber 208 can besquare to minimize head space. Alternatively, the plunger 192 can beshaped to occupy substantially all of the head space.

To retract the carriage 194, the plunger 190 is first moved distallywith a distally directed force F_(D) until the distal end surface of theplunger tip 192 contacts the shoulder 241 located at the interfacebetween the first engaging section 210 and the variable chamber 206. Atthis point, the end tip or distal tip 229 of the first tubular section230 of the plunger 190 contacts the holding tire 214 and the proximalend 231 of the carriage 194 contacts the tip of the plug 236. When anactuated force F_(A) is then applied on the plunger 190, the firsttubular section 230 of the plunger 190 moves over the proximal end ofthe carriage 194 in a telescoping fashion. At the same time, the plungertip 212 is compressed by the exterior shoulder 234 on the plunger 190and the shoulder 241 on the barrel 188.

Further plunger 190 distal movement causes the tip 229 of the tubularportion 230 to move the holding tire 214 distally off the base section222 of the carriage 194 and the base 238 of the plug 236 away from theinterior surface of the first tubular section 230. In one exemplaryembodiment, the holding tire 214 and the base 238 of the plug arereleased simultaneously from their respective seats when the plunger 190moves distally to retract the carriage 194. In an alternativeembodiment, the holding tire 214 moves off of its seat prior to the base238 of the plug 236 moves off of its seat. Still alternatively, the base238 of the plug 236 moves off of its seat prior to the holding tire 214moves off of its seat.

Once both the holding tire 214 and the plug 236 move off of theirrespective seats, the spring 196 is released and launches proximally inthe direction of the push flange 202. Because they are either directlyor indirectly in contact with the spring 196, the carriage 194, theneedle 226, and the plug 236 are also simultaneously launched distallyby the spring. The spring action thus retracts the needle 226 into theinterior cavity of the plunger 190 to thereby prevent accidental contactwith the needle tip (FIG. 13).

To further assist in securing the holding tire 214 against its seat,which is the mating surface area provided by the interior surface of thebarrel and the base 222 of the carriage 194, in one exemplaryembodiment, a projection 244 is incorporated at the shoulder 241 insidesurface of the barrel 188. The raised area 244 aids in snapping theholding tire 214 in place against the spring force when the plunger isin a withdrawn position.

In one exemplary embodiment, the plunger push flange 202 is seatedinside a recessed section 242 (FIGS. 12 and 13) of the enlarged barrelsection 200 of the barrel 188 following the retraction of the carriage.Because the push flange 202 incorporates a smooth contour, the plunger190 is made difficult to be grasped and moved proximally. In analternative embodiment, a detent engagement between the barrel and thepush flange may be incorporated to further deter access to the usedneedle.

An alternative automatic needle retract syringe 246 provided inaccordance with aspects of the invention is shown in FIGS. 14-15. Thesyringe 246 is substantially similar to the syringe 186 described abovewith reference to FIGS. 11-13 with the exception of the plunger tip 248and plunger first tubular section 230, which are different. In thepresent embodiment, the plunger tip 248 incorporates a pair of extensionlegs 250 a, 250 b and the first tubular section 230 of the plunger 190incorporates a flange 227. The extension legs 250 a, 250 b establish agap or space between the exterior shoulder 234 on the plunger 190 andthe plunger tip 248 when the syringe is in a ready to use position andduring an injection when a distally directed force F_(D) is applied. Theflange 227 of plunger 190 first tubular section 230 is positioned at theproximal end of space 251 inside the plunger tip 248. The flange 227secures the plunger tip 248 onto plunger 190 during aspiration of afluid, and in one exemplary embodiment comprises a tapered face on itsdistal side. However, when an actuated force F_(A) is applied on theplunger 190, the shoulder 234 bends the extension legs 250 a, 250 boutwardly to permit further distal movement of the plunger 190 relativeto the plunger tip to retract the carriage 194 (FIG. 15). Duringactivation, the flange 227 moves from a proximal position to a distalposition within the space 251 (FIG. 15).

In the ready to retract position (FIG. 14), the plunger tip 248, plug236, and first tubular section 230 of the plunger 190 should occupysubstantially all of the head space of the variable volume chamber tominimize fluid waste. In this configuration, the plunger tip 248 shouldbe in contact with the shoulder 252 on the barrel 188, the end tip 229of the plunger 190 should be in contact with the holding tire 214, andthe proximal end 231 of the carriage 194 should be in contact with theplug 236. Thus, as the plunger 190 is then moved distally to retract thecarriage 194, the extension legs 250 a, 250 b are bent outwardly by theshoulder 234, the holding tire 214 and the plug 236 are moved off oftheir respective seats, and the spring 196 is released to expand andretract the carriage 194 (FIG. 15) into the interior cavity of thebarrel 188.

FIGS. 16 and 17 show yet another alternative automatic needle retractsyringe 254 provided in accordance with aspects of the presentinvention. The syringe 254 is substantially similar to the syringes 186,246 described above with reference to FIGS. 11-15 with the exception ofthe plunger tip 256, which is different. In addition, the first tubularsection 230 of the plunger 190 has been slightly modified to cooperatewith the plunger tip 256, as further discussed below.

The plunger tip 256 in the present embodiment comprises a distal annularring 258 and a proximal annular ring 260, which define a space 262therein between. The distal and proximal annular rings 258, 260 form asize-on-size friction fit with the exterior surface of the first tubularsection 230 of the plunger. Internally, a projection 264 on the firsttubular portion 230 contacts the interior surface of the space 262 ofthe plunger tip 256. The contact between the interior surface of thespace 262 and the projection 264 provide added resistance againstmovement of the plunger tip 256 relative to the plunger 190 duringproximal movement of the plunger, i.e., during aspiration of a fluid. Inaddition, the projection 264 establishes a gap between the proximalannular ring 260 and the exterior shoulder 234 formed at theintersection of the first tubular portion 230 and the second tubularportion 232. Still further, the projection 264 facilitates aspiratingfluid into the syringe by securing the plunger tip 256 from falling offof the first tubular portion 230 when the plunger moves proximal.Alternatively, a second projection or flange 172 (as shown in FIGS. 7and 8) can be incorporated just proximal of the plunger tip 256, justproximal of the annular ring 260, to further secure the plunger tip 256on the plunger 190. If incorporated, the proximal annular ring 260 ofthe plunger tip 256 would be secured in the gap between both projections264 and 172.

When the plunger 190 is in position to retract the carriage 194 (FIG.16), the plunger tip 256, plug 236, and first tubular section 230 of theplunger 190 should occupy substantially all of the head space of thevariable volume chamber to minimize fluid waste. In this configuration,the plunger tip 256 should be in contact with the shoulder 252 on thebarrel 188, the end tip 229 of the plunger 190 should be in contact withthe holding tire 214, and the proximal end 231 of the carriage 194should be in contact with the plug 236. Thus, as the plunger 190 is thenmoved distally to retract the carriage 194, the actuated force F_(A)overcomes the friction between the plunger tip 256 and the first tubularportion 230 and allows the plunger 190 to move relative to the plungertip 256. Concurrently therewith, the holding tire 214 and the plug 236are moved off of their respective seats and the spring 196 is releasedto expand and retract the carriage 194 (FIG. 17) into the interiorcavity of the barrel. In the alternative embodiment (not shown), themost proximal projection 172 (as shown in FIGS. 7 and 8) would be forcedunder the proximal annular ring 260 when an actuated force F_(A) isapplied.

Turning now to FIG. 18, a syringe 266 for use with a needle hub 268having a spring loaded retractable needle 270 provided in accordancewith aspects of the present invention is shown. The barrel 272 in thepresent embodiment comprises an integrally molded Luer tip 274 and afemale lock 276 at the distal end 278 and a grip flange 280 at theproximal end 282. A plunger 284 is positioned internally of the barrel.The plunger 284 comprises an elongated tube 286 defining a bore 288, andfour rectangular plates or fins 290 attached to the tube 286 with boththe fins and tube attached to the push flange 292, which has an opening294 for molding the tube 286 and a frangible seal 296 for holding an endcap 297 at the distal end of the tube (FIGS. 18 and 19). Preferably, thebore 288 has a greater inside diameter than the end cap 297, for reasonsexplained below. The opening 294 is then sealed with a plug 298. Theplunger 284 also includes a push plate 300 and a distally projecting tipholder 302, which is located proximal of an extension pin 304, and whichmakes up part of the tube 286. The extension pin 304 is sized to fitwithin the Luer tip 274, which is sized to receive the needle hub 268,as further discussed below. In one exemplary embodiment, the elongatedtube 286 is cylindrical in shape. However, other elongated shaped bodiesmay be incorporated without deviating from the scope of the presentinvention.

The plunger tip 308 comprises an opening 310 for accommodating theextension pin 304, a proximal annular ring 312 forming a size-on-sizefriction fit with the tip holder 302, and a pair of proximally extendingextension legs 314 a, 314 b. In one exemplary embodiment, the extensionlegs 314 a, 314 b and the annular ring 312 contact both the push plate300 and the tip holder plate 316. However, a small gap between theannular ring 312 and the tip holder plate 316 is acceptable.

In one exemplary embodiment, the needle hub 268 useable with the syringe266 of the present embodiment comprises a housing 318, which comprises adistal housing structure 320 having a needle 270 protruding therefrom, aproximal housing structure 322 having male threads 320 thereon forthreaded engagement with the female lock 276, a central activationcompartment 324 disposed therebetween, and a bore 326 definedtherethrough. A generally cylindrical tube 323 with optional supportfins 325 are located at the distal end of the needle hub 268. The bore326 extends through the cylindrical tube 323 and has a size sufficientto accommodate the needle 270 and a spring 327, as further discussedbelow. At the distal end of the cylindrical tube 323 is an annular cap329 having a close tolerance fit with the outside diameter of the needle270. The annular cap 329 provides an anchor and supports one end of thespring 327, as further discussed below.

Exteriorly, the housing 318 is tapered inwardly in the direction fromthe proximal housing structure 322 towards the distal housing structure320, although a straight cylinder or wall may be acceptable. At thecentral activation compartment 324, the housing incorporates two wells328 a, 328 b (FIG. 19), which form two thin-walled sections 330 with thebore 326 of the hub 268. The thin-walled sections 330 each include abulge section 332 that forms a receiving space inside the bore 326 formating engagement with the needle sleeve 334, as further discussedbelow. Referring to FIG. 19 in addition to FIG. 18, the thin-walledsections 330 of the wells 328 a, 328 b each includes a base section 336,a transition section 338, which is tapered or angled from the basesection, and a gripping section 340, where the bulge 332 is located.Alternatively, a single well with a single thin-walled section may beincorporated in the needle hub.

The needle sleeve 334 (FIG. 19) comprises a generally elongated tubethat includes a bulge section 342 and a bore. In one exemplaryembodiment, the exterior surface 344 of the sleeve 334 comprises anundulating surface for increased gripping engagement with the grippingsections 340 of the wells 328 a, 328 b. To secure the needle 270 to thesleeve 334, the sleeve bore comprises a glue well 346 for gluing theneedle to the sleeve (FIG. 19).

To assemble the needle hub 268, the spring 327 is first mounted over thecombination needle 270 and needle sleeve 334. The needle 270 and spring327 are then inserted into the bore 326 of the needle hub 268 from theproximal end opening of the hub. The needle 270 is pushed distallythrough the bore 326 until the needle sleeve 334 engages the grippingsection 340 of the needle hub, at the two wells 328 a, 328 b. In oneexemplary embodiment, the engagement is achieved when the bulge 342 onthe sleeve 334 fits into the space provided by the bulge 332 of thegripping section 240.

To retract the needle 270, the plunger 284 is first moved distally witha distally directed force F_(D) until the distal end surface of theplunger tip 308 contacts the shoulder or end 348 of the barrel 272. Atthis point, the extension pin 304 is positioned inside the Luer tip 274with the end cap 297 on the extension pin 304 slightly spaced apart fromthe proximal end 350 of the needle 270 (FIG. 19). As an actuated forceF_(A) is then applied to the plunger 284, the push plate 300 movesdistally to bend the extension legs 314 a, 314 b inwardly (or outwardlyif the extensions legs 314 a, 314 b were positioned closer to the tipholder 302). Concurrently therewith, the extension pin 304 moves forwardand causes the transition section 338 of the wells 328 a, 328 b todeform outwardly to separate from the bulge 342 on the needle sleeve334. The forward motion also pushes the end cap 297 of the extension pin304 against the proximal end 350 of the needle 270. Because the needle270 is anchored by the needle sleeve 334 abutting against the hub 268,the needle 270 pushes back against the end cap 297 with an equal butopposite force and causes the frangible seal 296 to tear or separate.The proximal end 350 of the needle 270 eventually completely tears theend cap 297 from the extension pin 304, which then provides a passagefor the spring 327 to expand. The expanding spring 327 then pushes theneedle sleeve 336 proximally, which is attached to the needle 270 andpushes the needle proximally into the bore 288 located in the plunger284 to thereby prevent accidental contact with the needle tip. Once theneedle is retracted, the syringe may be safely disposed of per normalprotocols.

As best shown in FIGS. 18 and 20, when the actuated force F_(D) isapplied to the plunger 284 to retract the needle 270, the plunger movesdistally relative to the plunger tip 308. As discussed above, thisrelative movement is provided by a gap between the tip holder plate 316of the syringe tip holder 302 and the end surface 313 of the plunger tip308. Said gap should be of sufficient dimension so as to not delimit theproximal end 350 of the needle 270 from puncturing the frangible seal296.

Referring now to FIG. 21, an alternative syringe 352 for use with aneedle hub 268 having a spring loaded retractable needle 270 provided inaccordance with aspects of the present invention is shown. The syringe352 is substantially similar to the syringe 266 described above withreference to FIGS. 18-20 with the exception of the plunger tip 354,which is different. In addition, the tip holder 356 of the plunger 284has been slightly modified to cooperate with the plunger tip 354, asfurther discussed below.

The plunger tip 354 in the present embodiment comprises an internal bore358 comprising an internal diameter sized to frictionally engage theexterior surface of the tip holder 356. As before, a gap for relativemovement between the plunger tip 354 and the plunger 284 are providedinside the plunger tip bore, between the distal end of the tip holder356 and the end surface 360 of the plunger tip 354. The proximal end ofthe plunger tip 354 abuts the push plate 300 on the plunger 284. Thiscontact enables the push plate 300 to move the plunger tip 354 distallywhen a distally directed force F_(D) is applied, and to compress theplunger tip to retract the needle 270 when an actuated force F_(A) isapplied. The mechanism for retracting the needle 270 for the needle hub268 is the same as that discussed above with reference to the needle hubof FIGS. 18-20.

Turning now to FIG. 22, an alternative syringe 362 for use with a needlehub 268 having a spring loaded retractable needle 270 provided inaccordance with aspects of the present invention is shown. The syringe362 is substantially similar to the syringes 266, 352 described abovewith reference to FIGS. 18-21 with the exception of the plunger tip 364,which is different. In addition, the tip holder 366 of the plunger 284has been slightly modified to cooperate with the plunger tip 364, asfurther discussed below.

In the present embodiment, the plunger tip 364 incorporates a groove 368in the interior bore 358 of the plunger tip. The groove 368 is sized toreceive a plunger disc 370 on the plunger 284 and allows it to movedistally upon application of an actuated force F_(A) as described below.In one exemplary embodiment, the pusher plate 300 is located apart fromthe proximal annular ring 372 of the plunger tip 364 when in the readyto use position.

To retract the needle 270, the plunger is first advanced from a proximalto a distal position shown in FIG. 22. At this position, the end surface360 of the plunger tip 364 contacts the end shoulder 348 of the barrel272. When an actuated force F_(A) is then applied to the plunger 284,the plunger disc 370 moves distally within groove 368 of the plunger tip364 and the plunger 284 moves distally relative to the end surface 360of the plunger tip. The pusher plate 300 moves to meet the proximalannular ring 372 of the plunger tip 364. Concurrently therewith, theextension pin 304 contacts the needle 270 to retract the needle asdiscussed above with reference to FIGS. 18-20.

Turning now to FIG. 23, a partial cross-sectional view of an alternativeneedle hub 374 provided in accordance with aspects of the presentinvention is shown. The needle hub 374 is substantially similar to theneedle hub 268 described above with reference to FIGS. 18-20 with theexception of the way in which the gripping section 340 of the wells 328a, 328 b of the needle hub grips the needle 376. The needle hub 374 maybe used with any of the syringes 266, 352, 362 described above withreference to FIGS. 18, 21, and 22 and may be actuated to retract theneedle 376 the same way as described with those syringes 266, 352, 362.However, instead of utilizing a needle sleeve 334 (FIG. 19), in thepresent embodiment, the proximal end of the needle 376 incorporates acrimp or a bulge 378. The bulge or crimp 378 may be made by pinching theneedle to create a crimp or by a controlled compression process tocreate a bulge.

The needle hub 374 may be assembled by first positioning a spring 327over the needle 376, which then rests on an end against the bulge orcrimp 378. The combination needle 376 and spring 327 is then insertedinto the bore 326 of the needle hub and pushed distally until the bulgeor crimp 378 engages with the space provided by the bulge 332 formed inthe thin-walled sections 330 of the wells 328 a, 328 b. Once engaged,the crimp or bulge 378 and the annular ring or cap 329 on the tubesection 323 of the needle hub (See, e.g., FIG. 18) compresses the springand loads the needle 376 for retraction.

Yet another aspect of the present invention is the utilization ofprotective sheaths to shield the needle tips from accidental contacttherewith. One exemplary safety syringe assembly 380 comprising asyringe 382 and a protective sheath unit 384 is shown in FIG. 24. Theprotective sheath unit 384 is configured or sized to fit a standardsized syringe by incorporating provisions for receiving the standardsized syringe into the interior bore of the protective sheath unit 384to form the syringe assembly 380, as further discussed below.

The protective sheath unit 384 comprises a sheath cover 386telescopically positioned over an inner shell 394 (FIG. 25). In oneexemplary embodiment, the sheath cover 386 comprises an engagement base388 comprising a pair of opposed trigger levers 390 with each having areceptacle 391. The receptacle 391 on each trigger lever 390 isremovably engaged to an ear 392 located on the inner shell 394 to retainthe sheath cover 386 and the inner shell 394 in removable engagement,with reverse detent configuration being acceptable. The trigger levers390 may be formed by incorporating a pair of notches 396 a, 396 b to theengagement base 388 to create a pivot point or fulcrum 398. Each triggerlever 390 extends beyond the grip flange 400 at the proximal end 402 ofthe sheath cover 386 by a trigger tip 393. The trigger tip 393 has asufficient length to interact with an actuator 404 located on thesyringe 382 to launch the sheath cover, as further discussed below. Asreadily apparent to a person of ordinary skill in the art, one or morethan two trigger levers may be incorporated without deviating from thespirit and scope of the present invention.

The actuator 404 located on the plunger 406 just distal of the pushflange 408 is configured to release the receptacles 391 from the twoears 392 on the inner shell 394 to thereby release the sheath cover 386from the inner shell 394. In one exemplary embodiment, the actuator 404comprises a frustoconical front section 410 and a frustoconial basesection 412 separated from one another by an intermediate section 414.The actuator 404 is slidably mounted over the plunger 406 andfrictionally engaged thereto. More specifically, in one exemplaryembodiment, the actuator 404 comprises an inner shroud 416 comprising anopening sized to frictionally engage the elongated plates 55 a, 55 b ofthe plus (“+”)-shaped cross-section of the plunger 406. An annulargroove 418 between the inner shroud 416 and the frustoconical frontsection 410 allows the inner shroud 416 to flex when slid over theplunger, which may be further facilitated by optionally incorporating aplurality of slits or notches on the inner shroud 416 along thelengthwise or axial direction of the plunger to facilitate flexing.

The frustoconical front section 410 of the actuator 404 is configured topush the trigger tip 393 radially outwardly away from the axis definedby the plunger 406 to disengage the receptacles 391 from the ears 392.The actuator 404 may incorporate different configurations provided thereis a tapered distal surface, such as the frustoconical front section 410of the actuator 404 of FIG. 24. One such alternative is shown in FIG.26, which is a split actuator design. The split actuator 434 comprisestwo symmetrical actuator plates 436 each comprising a tapered pushsurface 438 and an engagement surface 440 comprising a full slot 442 anda part slot 444. The two part slots 444 on the two actuator plates 436form two full slots that together with the other two full slots 442engage the plus (“+”)-shaped cross-section of the plunger 406. The twoactuator plates 436 may be assembled over the plunger 406 by gluing orwelding the two tabs 446 of each actuator plate to the corresponding twotabs of the other actuator plate. Instead of or in addition thereto,detents may be used to attach the two actuator plates 436 together.Still alternatively, a tapered surface for actuating the trigger levers390 may be integrally molded to the plunger (not shown).

A cap cover 448 may be incorporated for covering the distal end of thesyringe 382 by removably engaging the cap base 450 of the cap cover tothe Luer lock on the syringe. The cap cover can be removed and discardedprior to mounting a needle and needle hub to the Luer lock (FIG. 25), asfurther discussed below.

In one exemplary embodiment, a distal stop lever 420 and a proximal stoplever 422 are incorporated on the sheath cover 386. The two stop levers420, 422 are formed by molding a pair of U-shaped notches 424 on thesheath cover 386 to create proximally facing levers having lever tips426, 428 and lever bases 429, which act as fulcrums. The two stop levers420, 422 are preferably formed along a common lengthwise surface of thesheath cover 396 and aligned with a rectangular slot 430 on the innershell 394, which is located subjacent the two levers 420, 422. Thelength of the levers 420, 422 measured from their respective bases 429to their respective tips 426, 428 can differ from one another and shouldbe of sufficient length so as to adequately permit the sheath cover 386to project relative to the inner shell 394 to shield the needle tip, asfurther discussed below. Although the two levers 420, 422 are shownaligned to the rectangular slot 430, only the distal stop lever 420should be aligned to the rectangular slot 430 and the proximal stoplever 422 may be positioned elsewhere on the sheath cover 386. Stillalternatively, the distal stop lever 420 may engage with a differentstructure than the rectangular slot 430 to delimit the forward distalmovement of the sheath cover. Still yet in another alternativeembodiment, an identical distal stop lever 420 and proximal stop lever422 are incorporated on an opposed surface of the sheath cover 430.

A cone section 432 is located distal of the two levers 420, 422 at thedistal most section of the sheath cover 386. The cone section 432 tapersinwardly from the periphery of the tubular section 433 of the sheathcover 386, which in one embodiment is generally cylindrical in shape.The cone section 432 includes an opening 452 dimensioned to accommodatethe Luer lock, as further discussed below. Optionally, the cone section432 may be eliminated and the tubular section 433 extended furtherdistally.

FIG. 25 is a semi-schematic cross-sectional side view of the safetysyringe assembly 380 of FIG. 24 taken from the same angle. In the readyto use position shown, the sheath cover 386 is spring loaded to theinner shell 394 via a compressed spring 454. More particularly, in oneexemplary embodiment, a shoulder 456 formed intermediate of the tubularsection 433 and the engagement base section 388 and the shoulder at theholding flange 458 at the proximal end of the inner shell 394 define acontainment space for containing the spring 454 in a compressedposition. The containment space is fixed or locked by the cooperationbetween the receptacles 391 on the trigger levers 390 and the ears 392on the inner shell 394 (FIG. 24), which maintains the spring in thecompressed configuration. Thus, when the ears 392 are disengaged fromthe receptacles 391, the spring is released and the sheath cover 386moves distally relative to the inner shell 394 to cover the needle, asfurther discussed below.

The inner shell 394 is sized to accommodate a standard sized syringe382, which can be made to accommodate any sizes. The inside diameter ofthe inner shell 394 should have an interference fit with the outersurface of the barrel 460 of the syringe. The standard sized syringe 382includes standard syringe components, such as a plunger 406, plunger tip462, and a barrel 460 having a Luer lock 464 and a Luer tip 466. TheLuer tip 466 is adapted to receive a needle hub 468 comprising a needle470, which is removeably secured to the barrel by threading to the Luerlock 464. Alternatively, the Luer lock can be eliminated and the opening452 on the sheath cover 386 made somewhat smaller.

To completely discharge fluid contained in the barrel or to completelyexpel air from the barrel prior to aspirating fluid into the barrelwithout activating the trigger levers 390 to release the sheath cover386, the plunger tip 462 incorporates a trigger gap and the plunger 406lengthens to accommodate the actuator 404. The trigger gap incorporatedin the plunger tip 462 is similar to the gap incorporated in the plungertips used with the syringes described above with reference to FIGS.1-22. In particular, the plunger tip 462 comprises an inward extendingring 78 sized to engage a groove defined by the proximal plunger disc172 and the distal plunger disc 174. The distal plunger disc 174 isspaced apart from the proximal interior wall 472 of the plunger tip 462by a gap. The gap, as previously discussed, allows the plunger 406 tomove distally relative to the exterior end wall 474 and proximalinterior wall 472 of the plunger tip 462 when an actuated force F_(A) isapplied.

In the fully expelled or discharged position shown in FIGS. 24 and 25,the ends of the two trigger tips 393 only slightly contact thefrustoconical front section 410 of the actuator 404 or is spaced apartfrom the surface of the frustoconical front section 410 by a small gap,in the order of a few mils to about ⅛ of an inch. This arrangementenables the plunger 406 to move the plunger tip 462 distally to fullyexpel or discharge fluid inside the syringe barrel 460 withouttriggering the trigger levers 390. Accordingly, in a preferredembodiment, there is a gap between the grip flange 476 of the syringeand the distal end of the inner shroud 416 of the actuator 404 that isless than the gap between the distal plunger disc 174 and the proximalinterior wall 472 of the plunger tip 462. As readily apparent to aperson of ordinary skill in the art, the gap and the angle of thefrustoconical front section 410 of the actuator 404 must cooperate tomove the trigger levers 390 radially outwardly a sufficient amount toclear the height of the ears 392 so that the receptacles 391 willseparate from the ears.

FIG. 27 is a semi-schematic cross-sectional side view of FIG. 25 takenalong line F27-F27. The safety syringe 380 is shown in an activatedstate just prior to launching the sheath cover 386 distally relative tothe inner shell 394 to cover the needle tip, which is shown in FIG. 28.The syringe 380 is activated by first moving the plunger 406 distallywith a distally directed force F_(D). This moves the plunger 406 untilthe plunger tip 462 abuts the end of the barrel 460 (FIG. 25). In aclinical situation, at this point, the needle 470 can be withdrawn froma subject or the spring can first be triggered as described below.

To cover the needle tip, an actuated force F_(A) is then applied on theplunger 406 to move the plunger relative to the plunger tip 462. Thisactuated force causes the inward extending ring 78 on the plunger tip462 to disengage from the groove defined by the proximal plunger disc172 and the distal plunger disc 174 on the plunger. Concurrentlytherewith, the actuator 404 moves distally and the frustoconical frontsection 410 pushes the trigger tips 393 of the trigger levers 390radially outwardly away from the axis defined by the needle 470 toseparate the ears 392 from the receptacles 391. The separation releasesthe restraint on the spring 454, which then expands and launches thesheath cover 386 distally relative to the inner shell 394 (FIG. 28). Thedistally travel of the sheath cover 386 is delimited by the two distalstop levers 420 located on the sheath cover, as previously discussed. Inparticular, the distal stop levers 420 each incorporates an inward tabor ear 478 at the lever tip 428 to abut the distal edge 480 (FIGS. 28and 29) of the rectangular slot 430 on the inner shell 394, whichcooperate to stop the distal travel of the sheath cover 386.

To prevent retracting the sheath cover 386 proximally after shieldingthe needle tip, the proximal stop levers 422 on the sheath cover engagethe distal end 482 of the inner shell 394. The proximal stop levers 422are molded with an inherent radial inward bias for flexing inwardly whentraveled distal of the inner shell 394. Thus, as the lever tips 426travel just distal of the distal edge 482 of the inner shell 394, theproximal stop levers 422 are unbiased and move to their normal radiallyinwardly position to cause the lever tips 426 to abut with the distaledge 482. This then delimits the sheath cover 386 from moving proximallyto expose the needle tip.

FIG. 29 is a semi-schematic perspective view of the inner shell 394provided in accordance with aspects of the present invention. The innershell 394 comprises a generally tubular shell, which in one exemplaryembodiment comprises a generally cylindrical shape. The inner shell 394has a holding flange 458 at its proximal end and a distal edge 482 atits distal end. A pair of ears 392 for cooperating with the receptacles391 on the trigger levers 390 are evenly spaced on the holding flange458. Although the holding flange 458 is shown as a continuous ring, anon-continuous ring, such as spaced apart ribs, may also beincorporated. To facilitate mounting the sheath unit 384 over a syringe,the inner shell 394 may incorporate longitudinal slots for addedflexibility.

The sheath unit 384 shown in FIGS. 24-29 are useable with varioussyringes, which in the preferred embodiment include syringes withtriggering mechanisms. For example, FIG. 30 shows the sheath unit 384 ofFIGS. 24-29 useable with an alternative syringe 484. The alternativesyringe 484, like the syringe of FIGS. 24-25, incorporates a plunger 406and plunger tip 34 having a trigger gap 486 to enable the safety syringeto completely discharge fluid or expel air prior to aspirating fluidwithout activating the sheath cover 386. Subsequent to an injection, thesheath unit 384 may be activated to shield the needle tip by applying anactivated force to move the plunger 406 relative to the plunger tip 34,as previously discussed. The plunger tip 34 shown is similar to theplunger tip described above with reference to FIGS. 1 and 2.

Other syringes useable with the sheath unit 384 include the syringedescribed with reference to FIGS. 24 and 25 having a syringe tip similarto any one of syringe tips described with reference to FIGS. 3-22.

Although limited embodiments of the syringe assemblies and theircomponents have been specifically described and illustrated herein, manymodifications and variations will be apparent to those skilled in theart. Accordingly, it is to be understood that the syringe assemblies andtheir components constructed according to principles of this inventionmay be embodied other than as specifically described herein. Theinvention is defined in the following claims.

1. A syringe assembly comprising: a syringe comprising a barrel havingan open proximal end and a barrel end surface at a distal end, a plungerslidably disposed in the barrel comprising a push flange, and a plungertip comprising a plunger tip end surface positioned on a distal end ofthe plunger; the push flange being spaced apart from the plunger tip endsurface by a first distance; a sheath unit comprising a sheath covertelescopically disposed over and removably secured to an inner shell;said inner shell comprising an interior surface defining an interiorcavity; a spring compressed by a shoulder on the sheath cover and ashoulder on the inner shell; wherein the barrel is disposed, at least inpart, in the cavity of the inner shell; and wherein the plungercomprises three plunger positions including a first plunger position inwhich the plunger tip positioned on the plunger is spaced apart from thebarrel end surface; a second plunger position in which the plunger tipcontacts the barrel end surface; and a third plunger position in whichthe push flange on the plunger moves a distal direction relative to theplunger tip distal end surface such that the push flange is now spacedapart from the plunger tip distal end surface by a second distance,which is less than the first distance.
 2. The syringe assembly of claim1, wherein the sheath cover comprises an engagement base sectioncomprising a first diameter and a tubular section comprising a seconddiameter section.
 3. The syringe assembly of claim 2, wherein the firstdiameter is larger than the second diameter.
 4. The syringe assembly ofclaim 3, wherein the spring is constrained on one end by the shoulderlocated in the base section.
 5. The syringe assembly of claim 1, furthercomprising at least one trigger lever located on the sheath cover. 6.The syringe assembly of claim 5, wherein the at least one trigger levercomprises a receptacle.
 7. The syringe assembly of claim 1, wherein theinner shell comprises an ear for removably securing to the sheath cover.8. The syringe assembly of claim 1, wherein the barrel comprises a Luerlock.
 9. The syringe assembly of claim 8, further comprising a needlemounted to a needle hub threadably engaged to the Luer lock.
 10. Thesyringe assembly of claim 1, wherein the plunger tip is mounted on a tipholder.
 11. The syringe assembly of claim 10, wherein the tip holdercomprises two generally parallel plunger discs defining a groove. 12.The syringe assembly of claim 11, wherein the plunger tip comprises aninwardly extending ring engaged to the groove.
 13. The syringe assemblyof claim 1, wherein the plunger tip comprises to two extension legs. 14.The syringe assembly of claim 1, wherein the plunger tip comprises aproximal end surface abutting a plunger disc located on a tip holder.15. The syringe assembly of claim 1, further comprising a taperedactuating surface located on the plunger for disengaging the sheathcover from the inner shell.
 16. The syringe assembly of claim 15,wherein the tapered actuating surface is integrally molded to theplunger.
 17. The syringe assembly of claim 15, wherein the taperedactuating surface is slidably mounted on the plunger.
 18. The syringeassembly of claim 15, wherein the tapered actuating surface is assembledover the plunger by placing two actuator plates together.
 19. Thesyringe assembly of claim 1, further comprising a distal stop lever anda proximal stop lever located on the sheath cover.
 20. The syringeassembly of claim 19, wherein the inner shell comprises a rectangularslot.
 21. The syringe assembly of claim 20, wherein the distal stoplever cooperates with the rectangular slot to stop the sheath cover frommoving distally.
 22. The syringe assembly of claim 21, wherein theproximal stop lever cooperates with an end edge of the inner shell tostop the sheath cover from moving proximally.
 23. The syringe assemblyof claim 22, wherein the sheath cover comprises at least one triggerlever, the inner shell comprises an engagement surface, and wherein theat least one trigger lever engages with the engagement surface.
 24. Thesyringe assembly of claim 1, wherein the sheath cover comprises atapered cone section on a distal end.
 25. A syringe assembly comprising:a syringe comprising a barrel and a plunger having a plunger tipdisposed inside the barrel; wherein the plunger comprises a taperedtrigger element disposed distal of a plunger push surface and the barrelcomprising a barrel end surface comprising an orifice; a sheath unitcomprising a sheath cover comprising at least one trigger levercomprising a pivot point and a trigger tip; the sheath cover beingtelescopically disposed over an inner shell and removably held theretoby a detent engagement between the trigger lever and an engagementsurface on the inner shell; a spring held in a compressed configurationby the detent engagement; wherein the syringe is disposed, at least inpart, inside the inner shell; and wherein the plunger tip abuts thebarrel end surface and the tapered trigger element on the plungercontacts the trigger lever but does not sever the detent engagement. 26.The syringe assembly of claim 25, wherein tapered trigger element on theplunger severs the detent engagement when the plunger moves distalrelative to an exterior wall surface of the plunger tip.
 27. The syringeassembly of claim 25, wherein the trigger lever comprises a receptacleand the inner shell comprises an ear, and wherein the detent engagementcomprises the ear engaging the receptacle.
 28. The syringe assembly ofclaim 26, wherein the tapered trigger element severs the detentengagement by pushing the trigger lever radially outwardly about thepivot point.
 29. The syringe assembly of claim 25, wherein the plungertip comprises a trigger gap defined by a space between an end surface ofa tip holder and an interior surface of the plunger tip.
 30. The syringeassembly of claim 25, wherein the plunger tip is axially compressible topermit relative movement between the plunger and an exterior wallsurface of the plunger tip.
 31. The syringe assembly of claim 25,further comprising a proximal stop lever and a distal stop lever on thesheath cover.
 32. The syringe assembly of claim 25, wherein the innershell comprises a rectangular slot.
 33. The syringe assembly of claim25, wherein the barrel comprises a Luer lock.
 34. The syringe assemblyof claim 25, wherein the tapered trigger element is integrally molded tothe plunger.
 35. A syringe assembly comprising: a syringe disposed, atleast in part, inside an interior cavity of a sheath unit; the syringecomprising a barrel comprising an open proximal end and a closed distalend comprising an orifice; a plunger comprising a push flange, a taperedactuator, and a tip holder comprising a plunger tip mounted thereonslidably disposed inside the barrel; the push flange being spaced apartfrom a distal exterior wall surface of the plunger tip by a firstdistance; the sheath unit comprising a spring and a sheath covertelescopically disposed over an inner shell and held to the inner shellby an engagement between a receptacle on a trigger lever located on thesheath cover engaging an ear located on the inner shell; the springbeing held in a compressed configuration by the engagement; wherein thetapered actuator disengages the ear from the receptacle when the plungermoves distally and the push flange is spaced apart from the distalexterior wall surface by a second distance, which is less than the firstdistance.
 36. The syringe assembly of claim 35, wherein the barrelcomprises a Luer lock.
 37. The syringe assembly of claim 35, wherein theplunger tip is axially compressible.
 38. The syringe assembly of claim35, wherein the outer shell comprises a distal stop lever and a proximalstop lever.
 39. The syringe assembly of claim 35, wherein the taperedactuator is integrally molded to the plunger.
 40. The syringe assemblyof claim 35, wherein the trigger lever moves radially outwardly whencontacted by the actuator.